Nowadays, electronic circuits may store sensitive data such as banking information, passwords, registration codes, and so forth, which may be stolen by unauthorized attackers. Therefore, protection of sensitive data has gained increasing attention, and various forms of security protection devices and methods have emerged. For example, an anti-tampering method for protecting sensitive data uses several printed circuit boards to form an anti-tampering enclosure to enclose a protected region containing the sensitive data. The anti-tampering enclosure includes a base printed circuit board, which is peripherally enclosed by one or more additional printed circuit boards and is covered by yet another printed circuit board. The printed circuit boards included in the anti-tampering enclosure are configured as a multilayered structure, such that the enclosure has gaps between the layers. As a result, an attacker may be able to gain access to the protected region through the gaps, and thus security risks still remain.